Metalized ceramic substrates, also referred to as printed circuit boards, having a thick copper layer (typically 200 to 300 μm) are required for power electronic applications, to ensure the required current-carrying capacity. The power semiconductor is soldered upon these. Only comparatively large conductor widths and distances can be implemented on these thick copper structures.
An electronic circuit is required to control the power semiconductor. The components used for this purpose (microcontroller, bus coupler, etc.) and metalized carrier substrates of same have finer and thinner electrical conducting paths and pitch spacings than the carrier substrates for power components. Therefore, they are mounted on a separate metalized substrate. Both carrier substrates are electrically connected with each other via wires. These connections age and incline to failure, which results in breakdown of the entire power module.
Metalizations generally denote electrical conducting paths and planar metalizations on ceramic substrates, in which the conducting paths serve to conduct current and the planar metalizations function, for example, to solder the power semiconductors and connecting elements. Multi-level metalization on a ceramic substrate is understood as metalization of varying thickness. The thickness of the metalization is the extension thereof perpendicular to the surface of the ceramic substrate. This thickness is also described in terms of height or strength.
Another hitherto scarcely used method consists in the application of an electrically insulating layer structured photochemically or by screen printing technology onto the thin copper layer of a conducting path with further electrochemical deposition of copper on the areas left blank. To date, the production of such a multi-stage substrate still requires an expensive galvanic processing and a multiple structuring with plating resists and photo-optical development and stripping of the resist.